.\" Copyright (C) 2002, Michael Kerrisk
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" Modified 31 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
.\"	Added description of mmap2
.\" Modified, 2004-11-25, mtk -- removed stray #endif in prototype
.\"
.TH mmap2 2 2023-02-10 "Linux man-pages 6.03"
.SH NAME
mmap2 \- map files or devices into memory
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.BR "#include <sys/mman.h>" "    /* Definition of " MAP_* " and " PROT_* " constants */"
.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
.B #include <unistd.h>
.PP
.BI "void *syscall(SYS_mmap2, unsigned long " addr ", unsigned long " length ,
.BI "              unsigned long " prot ", unsigned long " flags ,
.BI "              unsigned long " fd ", unsigned long " pgoffset );
.fi
.SH DESCRIPTION
This is probably not the system call that you are interested in; instead, see
.BR mmap (2),
which describes the glibc wrapper function that invokes this system call.
.PP
The
.BR mmap2 ()
system call provides the same interface as
.BR mmap (2),
except that the final argument specifies the offset into the
file in 4096-byte units (instead of bytes, as is done by
.BR mmap (2)).
This enables applications that use a 32-bit
.I off_t
to map large files (up to 2\[ha]44 bytes).
.SH RETURN VALUE
On success,
.BR mmap2 ()
returns a pointer to the mapped area.
On error, \-1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EFAULT
Problem with getting the data from user space.
.TP
.B EINVAL
(Various platforms where the page size is not 4096 bytes.)
.I "offset\ *\ 4096"
is not a multiple of the system page size.
.PP
.BR mmap2 ()
can also return any of the errors described in
.BR mmap (2).
.SH VERSIONS
.BR mmap2 ()
is available since Linux 2.3.31.
.SH STANDARDS
This system call is Linux-specific.
.SH NOTES
On architectures where this system call is present,
the glibc
.BR mmap ()
wrapper function invokes this system call rather than the
.BR mmap (2)
system call.
.PP
This system call does not exist on x86-64.
.PP
On ia64, the unit for
.I offset
is actually the system page size, rather than 4096 bytes.
.\" ia64 can have page sizes ranging from 4 kB to 64 kB.
.\" On cris, it looks like the unit might also be the page size,
.\" which is 8192 bytes. -- mtk, June 2007
.SH SEE ALSO
.BR getpagesize (2),
.BR mmap (2),
.BR mremap (2),
.BR msync (2),
.BR shm_open (3)
